No. 2.] LARVA OF CTENOPHORA ANGUSTIPENNIS. 551 
the anterior portion. The two collecting ducts unite to form 
a common duct which lies just beneath the cesophagus and 
opens at the base of the hypopharynx. The glands are hollow, 
the walls being only one cell thick. The cell wall consists 
merely of an epithelial layer with its intima and basement 
membrane. As seen in a surface view the cells are very large 
and polygonal in shape. (Fig. 34.) They possess very large 
nuclei in which a distinct chromatic filament can easily be made 
out by proper staining. The breaking down of the salivary 
gland is accompanied apparently by simple cell degeneration, 
the “‘selbstandige’’ degeneration of Karawaiew, and therefore 
without the recurrence of phagocytosis. The cell nuclei are 
at first regularly circular and sharply marked out by a nuclear 
membrane, but later on the nucleus loses this membrane. 
(Fig. 35.) The histolysis here follows closely the course 
described by Kellogg in regard to Holorusia. (Am. Nat., 
1901.) Of course in the case of such a generalized larva as 
that of Ctenophora the breakdown of the larval organs would 
be accomplished with less change of structure than in the 
more specialized forms, which have been largely the forms 
studied in this connection, and so there would be less reason 
for the occurrence of phagocytosis. 
VE Por TRacHvan SYStem 
There are two main lateral trachez, one passing along each 
side of the medio-dorsal line. These main divisions of the 
respiratory system are seen very clearly when looking at the 
live larve, and appear as two glistening bands when the animal 
is expanded, but having a sinuous course when the animal is 
contracted. These two trachez are connected by transverse 
and anastomosing branches, one main connecting branch in 
each segment. These branches, as well as the lateral tubes, 
give off numerous side branches. As these commissures are 
connected with the alimentary canal they are very slack, espe- 
cially those near the middle of the body. During the vermi- 
form movements of the larva, there is a great deal of sliding 
